Platform tunnels and Access tunnels and Switch tunnels and Tail tunnel in the stations in the framework of İzmir 4th Phase F.Altay-Narlıdere Kaymakamlık Construction Work Project shall be constructed with NATM method.


TBM (Tunnel Boring Machine); accommodated the technology required for tunnel construction inside a ring having a spherical cylindrical form in a dimension designed to be built. Machine’s cylindrical form ensures that the excavated soil stability is maintained.

The thrust rollers on the CPC for the excavation process, based on the concrete segments, push the cutter head towards the faceplate and the head starts to rotate. Excavation is stopped after the necessary clearance has been provided for the placement of the concrete segments. By means of pressurized erectors on the TBM, the concrete segments are placed on the tunnel wall and assembled to each other by means of bolts. Concrete injection between the excavation surface and the segments is done and the fortification process is finalized.

Within the scope of the project, 2 CPCs will be used and the line tunnels forming the route will be constructed by excavating with TBM.


The excavation gap planned to be excavated in this method is supported by reinforced concrete pile or reinforced concrete curtain wall. If the ground water is close to the surface, the ground water level is reduced or water is drained into the deep wells. After drawing the piles, the excavation works are started and the excavation works are started with the required level anchor and the excavation works continue until the foundation level. Then the work is completed and backfill is done by making the reinforced concrete productions from the foundation.

The entrance / exit structures of the stations and the concave structures with the ticket halls shall be constructed by cut / cover method.